Heart repair difficulties Heart nanotechnology

1 heart repair difficulties

1.1 heart patches
1.2 tissue scaffolds
1.3 nanoparticles

1.3.1 composition
1.3.2 research


1.4 polyketal nanoparticles

1.4.1 composition
1.4.2 use in myocardial infarction

heart repair difficulties

being able fix cardiac tissue has been damaged heart attack or heart disease not simple , 1 of major challenges today in field of tissue engineering ( popular science ). because heart cells not easiest objects create in lab. takes enormous amount of special care , work develop cells beat in sync 1 ( popular science ). after heart cells have been made, large task insert cells inoperable parts of heart , them working in unison tissues still working ( popular science ).

heart patches

there have been several successful examples of use of stem-cell- based heart patch developed duke university researchers, ( popular science ). biomaterials make patch made of either biological polymers alginate or synthetic polymers such polylactic acid ( nature nanotechnology ). these materials @ organizing cells functioning tissues; act insulators , poor conductors of electricity, major problem in heart ( nature nanotechnology ). since electrical signals sent between calcium ions control when cardiomyocytes of heart contract, makes heart beat, stem-cell heart patch not efficient , not effective doctors ( popular science ). results of patch not being conductive cells not able attain smooth, continuous beat throughout entire tissue containing stem cells. results in heart not functioning properly, in turn mean more heart problems might arise due implanting of stem cells.

tissue scaffolds

recently there have been new developments in field of nanotechnology more efficient poorly conducting stem-cell-based patch ( nature nanotechnology ). scientists , researchers found way these stem cell patches (also known tissue scaffolds) conductive , therefore become exponentially more effective ( nature nanotechnology ). found growing gold nanowires , through patches, able increase electrical conductivity. nanowires thicker original scaffold , cells better organized well. there increase in production of proteins needed muscle calcium binding , contraction. gold nanowires poke through stem cell s scaffolding material, strengthens electrical communication between surrounding heart cells. without nanowires, stem cell patches produced minute current , cells beat in small clusters @ stimulation origin. nanowires, cells seem contract when clustered far away source of stimulation. use of gold nanowires stem cell heart patches still relatively new concept , awhile before used in humans. hoped nanowires tested in live animals in near future.

nanoparticles

another way nanotechnology potentially used fix damaged heart tissues through use of guided nanoparticle missiles . these nanoparticles can cling , attach artery walls , secrete medicine @ slow rate ( mit-massachusetts institute of technology ). particles, known nanoburrs due fact coated little protein fragments stick , target proteins. nanoburrs can made release drug attached them on course of several days ( mit-massachusetts institute of technology ). unique compared regular drugs because can find particular damaged tissue, attach it, , release drug payload attached ( mit-massachusetts institute of technology ). happens nanoburrs targeted structure, known basement membrane; membrane lines arterial walls , present if area damaged. nanoburrs able carry drugs effective in treating heart, , potentially carry stem cells regenerate damaged heart tissue ( mit-massachusetts institute of technology ).

composition

the particles made of 3 different layers , sixty nanometers in diameter ( mit-massachusetts institute of technology ).the outer layer coating of polymer called peg, , job protect drug disintegrating while traveling through body. middle layer consists of fatty substance , inner core contains actual drug along polymer chain, controls amount of time take before drug released ( mit-massachusetts institute of technology ).

research

in study done on rats, nanoparticles injected directly rat s tail , still able reach desired target (the left carotid artery) @ rate twice amount of non-targeted nanoparticles ( mit-massachusetts institute of technology ). because particles can deliver drugs on long period of time, , can injected intravenously, patients not need have multiple repeated injections, or invasive surgeries on heart lot more convenient. downside existing delivery approaches invasive, requiring either direct injection heart, catheter procedures, or surgical implants. there no question, however, future of heart repairs , heart disease/attack prevention involve use of nanotechnology in way.

polyketal nanoparticles
composition

polyketal nanoparticles ph-sensitive, hydrophobic nanoparticles formulated poly(1-4-phenyleneacetone dimethylene ketal). acid-sensitive vehicle of drug delivery, designed targeting environments of tumors, phagosomes, , inflammatory tissue. in such acidic environments, these nanoparticles undergo accelerated hydrolysis low molecular weight hydrophilic compounds, consequently releasing therapeutic contents @ faster rate. unlike polyester-based nanoparticles, polyketal nanoparticles not generate acidic degradation products following hydrolysis

use in myocardial infarction

post-myocardial infarction, inflammatory leukocytes invade myocardium. leukocytes contain high amounts of nicotinamide adenine dinucleotide phosphate (nadph) , nox2. nox2 , nadph oxidase combine act major source of cardiac superoxide production, in excess can lead myocyte hypertrophy, apoptosis, fibrosis, , increased matrix metalloproteinase-2 expression. in mouse-model study somasuntharam et al. 2013, polyketal nanoparticles used delivery vehicle sirna target , inhibit nox2 in infarcted heart. following intramyocardial injection in vivo, nox2-sirna nanoparticles prevented upregulation of nox2-nadph oxidase, , improved fractional shortening. when taken macrophages in myocardium following mi, nanoparticles degraded in acidic environment of endosomes/phagosomes, releasing nox2-specific sirna cytoplasm.

polyketal nanoparticles have been used in infarcted mouse heart prevent ischemia-reperfusion injury caused reactive oxygen species (ros). levels of antioxidant cu/zn-superoxide dismutase (sod1), scavenges harmful ros, decrease following mi. sod1-enacapsulated polyketal nanoparticles able scavenge reperfusion-injury induced ros. furthermore, treatment improved fractional shortening, suggesting benefit of targeted delivery polyketals. 1 of key advantages of polyketal use not exacerbate inflammatory response, when administered @ concentrations exceeding therapeutic limits. in contrast commonly used poly(lactic-co-glycolic acid) (plga) nanoparticles, polyketal nanoparticle administration in mice instigates little recruitment of inflammatory cells. additionally, intramuscular injection of polyketals leg of rats shows no significant increases in inflammatory cytokines such il-6, il-1ß, tnf-α , il-12.